A significant amount of sailboat technology has been directed toward increasing the speed of a sailboat under various operating conditions. Toward that end, the configuration of the sailboat hull, as well as the size, configuration, and relative placement of the sails and accessory equipment have all been the subject of a significant amount of design effort and experimentation. The increasing number and significance of various sailboat races is an additional incentive to increase sailboat speed.
However, relatively little effort or experimentation has been directed toward enhancing the flow of air past the sails although there are devices commercially available which are of assistance in making maximum use of the available wind, i.e. to permit sailing as close to the wind as possible. An example of such a device is the strips or tufts of material which are positioned at spaced locations over the area of the sail, which provide an indication of the optimum position of the sail relative to the direction of the wind when they are extending outwardly from the surface of the sail. Still other devices are used to accurately determine wind direction, so that the sails can be controlled accordingly, as well as numerous devices to assist in the convenient control of the position of the sails.
The inventors, however, have experimented with enhancing the airflow past the sails. In studying the airflow from an aerodynamic viewpoint, they have discovered that sailboats are typically hindered in making maximum use of the available wind because a sail per se is in essence a high speed airfoil section, as shown in FIG. 1. A high speed section is characterized by a narrow leading edge, and a sail inherently has a narrow leading edge, as does the typically correspondingly narrow forestay which extends the length of the sail and secures the leading edge of the sail to the boat.
Such a narrow leading edge is often disadvantageous for a sail, however, as it significantly limits the angle over which the sail can perform without stalling when the boat is sailing close to the wind. Turbulent water or other operating variables will frequently induce a stall and turbulent airflow across the sail will also result in a loss of boat speed.
A narrow leading edge was discovered by the inventors to have an additional disadvantage in that a narrow leading edge is suited for high speeds, beyond that of sailboats, which results again in the maximum effect of existing wind not being obtained. In summary, the inventors have found that a narrow leading edge is rarely, if ever, desirable for a sail.